Building a TC with enemy lush (Gaia) underneath?

Hey guys, it seems like around half the time I try to build a TC where Gaia has previously built a TC, it won't let me. I used to think you just couldn't rebuild a TC where Gaia had held a TC, but recently I started seeing it happen more. I've probably asked about 10 times in game but I've never gotten even an acknowledgement. Does anyone know the mechanics here?